Measuring apparatus and measuring method

Abstract

A measuring apparatus is provided that includes: a timing jitter calculator for calculating the first timing jitter sequence of the first signal and the second timing jitter sequence of the second signal; and a jitter transfer function estimator for calculating a jitter transfer function between the first and second signals based on frequency components of the first and second timing jitter sequences. The jitter transfer function estimator calculates the jitter transfer function, for a plurality of frequency component pairs each of which is formed by a frequency component of a timing jitter in the first timing jitter sequence and a frequency component of a timing jitter in the second timing jitter sequence which correspond to approximately equal frequencies, based on frequency component ratios of the timing jitters in the first and second timing jitter sequences.

1. A measuring apparatus for measuring jitter characteristics of an electronic circuit, comprising:
 a timing jitter calculator operable to calculate a first timing jitter sequence of a first signal and a second timing jitter sequence of a second signal, said first signal being supplied to said electronic circuit or generated by said electronic circuit, said second signal being generated by said electronic circuit; and 
 a jitter transfer function estimator operable to calculate a jitter transfer function between said first signal and said second signal based on frequency components of said first and second timing jitter sequences. 
 
   
   
     2. A measuring apparatus as claimed in  claim 1 , wherein said jitter transfer function estimator calculates said jitter transfer function based on a ratio of a frequency component of a timing jitter in said first timing jitter sequence and a frequency component of a timing jitter in said second timing jitter sequence, said timing jitter in said first timing jitter sequence and said timing jitter in said second timing jitter sequence having approximately equal frequencies. 
   
   
     3. A measuring apparatus as claimed in  claim 2 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said jitter transfer function estimator calculates said jitter transfer function, for a plurality of frequency component pairs each of which is formed by a frequency component of a timing jitter in said first timing jitter sequence and a frequency component of a timing jitter in said second timing jitter sequence which correspond to approximately equal frequencies, based on frequency component ratios of said timing jitters in said first and second timing jitter sequences. 
 
   
   
     4. A measuring apparatus as claimed in  claim 3 , wherein said timing jitter calculator calculates said first timing jitter sequence while using an input signal supplied to said electronic circuit as said first signal. 
   
   
     5. A measuring apparatus as claimed in  claim 1 , wherein said first signal is an input signal supplied to said electronic circuit, and
 said measuring apparatus further comprises a jitter incorporating unit operable to incorporate a desired input timing jitter into said input signal. 
 
   
   
     6. A measuring apparatus as claimed in  claim 1 , wherein said jitter transfer function estimator includes a timing jitter spectrum calculator operable to receive said first and second timing jitter sequences and to calculate frequency components of said first and second timing jitter sequences. 
   
   
     7. A measuring apparatus as claimed in  claim 5 , wherein said jitter incorporating unit incorporates said input timing jitter having a plurality of frequency components into said input signal. 
   
   
     8. A measuring apparatus as claimed in  claim 1 , wherein said jitter transfer function estimator includes:
 a power spectrum calculator operable to calculate a power spectrum of said first timing jitter sequence or said second timing jitter sequence; 
 a cross spectrum calculator operable to calculate a cross spectrum between said first timing jitter sequence and said second timing jitter sequence; and 
 a jitter transfer function calculator operable to calculate said jitter transfer function based on a ratio of said power spectrum to said cross spectrum. 
 
   
   
     9. A measuring apparatus as claimed in  claim 1 , further comprising a jitter related transmission penalty calculator operable to calculate jitter related transmission penalty of said electronic circuit based on said jitter transfer function. 
   
   
     10. A measuring apparatus as claimed in  claim 9 , wherein said jitter related transmission penalty calculator includes a bit error rate calculator operable to calculate a bit error rate of said electronic circuit based on said jitter transfer function. 
   
   
     11. A measuring apparatus as claimed in  claim 9 , wherein said jitter related transmission penalty calculator includes a jitter tolerance calculator operable to calculate jitter tolerance of said electronic circuit based on said jitter transfer function. 
   
   
     12. A measuring apparatus as claimed in  claim 10 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said bit error rate calculator calculates a worst-case value of said bit error rate for said plurality of frequency components. 
 
   
   
     13. A measuring apparatus as claimed in  claim 12 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said bit error rate calculator further calculates a mean value of said bit error rate for said plurality of frequency components. 
 
   
   
     14. A measuring apparatus as claimed in  claim 12 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said bit error rate calculator further calculates said bit error rate in a case where a sinusoidal jitter was incorporated as an input timing jitter into an input signal of said electronic circuit, for said plurality of frequency components. 
 
   
   
     15. A measuring apparatus as claimed in  claim 14 , wherein said bit error rate calculator calculates performance limit of said bit error rate of said electronic circuit in the case where said sinusoidal jitter was incorporated as said input timing jitter. 
   
   
     16. A measuring apparatus as claimed in  claim 11 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said jitter tolerance calculator calculates a worst-case value of said jitter tolerance for said plurality of frequency components. 
 
   
   
     17. A measuring apparatus as claimed in  claim 16 , wherein each of said first and second timing jitter sequences includes a plurality of frequency components, and
 said jitter tolerance calculator further calculates a mean value of said jitter tolerance for said plurality of frequency components. 
 
   
   
     18. A measuring apparatus as claimed in  claim 16 , wherein said jitter tolerance calculator calculates said jitter tolerance of said electronic circuit in the case where said sinusoidal jitter was incorporated as an input timing jitter. 
   
   
     19. A measuring apparatus as claimed in  claim 18 , wherein said jitter tolerance calculator calculates performance limit of said jitter tolerance of said electronic circuit in the case where said sinusoidal jitter was incorporated as said input timing jitter. 
   
   
     20. A measuring apparatus as claimed in  claim 5 , wherein said jitter incorporating unit incorporates said timing jitter into said input signal by performing phase modulation of said input signal. 
   
   
     21. A measuring apparatus as claimed in  claim 5 , wherein said jitter incorporating unit incorporates said timing jitter into said input signal by performing frequency modulation of said input signal. 
   
   
     22. A measuring apparatus as claimed in  claim 5 , wherein said second signal is an output signal output from said electronic circuit,
 said jitter incorporating unit incorporates a plurality of input timing jitters having different amplitudes into said input signal, said amplitudes being within a region where a relationship between said input timing jitters and output timing jitters of said output signal is linear, and 
 said jitter transfer function estimator includes a gain calculator operable to calculate a gain of said jitter transfer function by performing linear approximation of a relationship between timing jitter values in said first timing jitter sequence and timing jitter values in said second timing jitter sequence, said timing jitter values in said first and second timing jitter sequences being made to correspond to said respective amplitudes of said input timing jitters. 
 
   
   
     23. A measuring apparatus as claimed in  claim 22 , wherein said jitter transfer function estimator further includes a timing phase difference calculator operable to calculate a phase difference between said input timing jitters and said output timing jitters. 
   
   
     24. A measuring apparatus as claimed in  claim 1 , wherein said timing jitter calculator includes:
 an analytic signal transformer operable to transform said first and second signals to an analytic signal that is a complex number; 
 an instantaneous phase estimator operable to estimate an instantaneous phase of said analytic signal based on said analytic signal; 
 a linear instantaneous phase estimator operable to estimate a linear instantaneous phase of each of said first and second signals based on said instantaneous phase of said analytic signal; and 
 a linear trend remover operable to calculate an instantaneous phase noise, that is obtained by removing said linear instantaneous phase from said instantaneous phase, based on said instantaneous phase and said linear instantaneous phase for each of said first and second signals. 
 
   
   
     25. A measuring apparatus as claimed in  claim 24 , wherein said timing jitter calculator further includes a resampler operable to receive said instantaneous phase noise of each of said first and second signals and to calculate said first and second timing jitter sequences by resampling said received instantaneous phase noise. 
   
   
     26. A measuring apparatus as claimed in  claim 25 , wherein said resampler re-samples said instantaneous phase noise at times approximately the same as zero-crossing times of a corresponding one of said first and second signals. 
   
   
     27. A measuring apparatus as claimed in  claim 24 , wherein said analytic signal transformer includes:
 a bandwidth limiter operable to extract, from each of said first and second signals, frequency components containing a fundamental frequency of a corresponding one of said first and second signals; and 
 a Hilbert transformer operable to generate, for each of said first and second signals, a Hilbert pair obtained by performing Hilbert transform of said frequency components extracted by said bandwidth limiter, and 
 wherein said analytic signal transformer outputs said Hilbert pair as an imaginary part of said analytic signal. 
 
   
   
     28. A measuring apparatus as claimed in  claim 24 , wherein said analytic signal transformer includes:
 a time-domain to frequency-domain transformer operable to transform each of said first and second signals to a two-sided spectrum in frequency domain; 
 a bandwidth limiter operable to extract frequency components of said two-sided spectrum, said frequency components containing a positive fundamental frequency; and 
 a frequency-domain to time-domain transformer operable to output as said analytic signal a signal obtained by transforming said frequency components extracted by said bandwidth limiter into time domain. 
 
   
   
     29. A measuring apparatus as claimed in  claim 24 , wherein said analytic signal transformer includes:
 a buffer memory operable to store said first and second signals; 
 a waveform data selector operable to sequentially select apart of said first and second signals stored in said buffer memory; 
 an window function multiplier operable to multiply said signal part selected by said waveform data selector by a predetermined window function; 
 a time-domain to frequency-domain transformer operable to transform said signal part multiplied by said window function to a spectrum in frequency domain; 
 a bandwidth limiter operable to extract frequency components of said spectrum, said frequency components containing a positive fundamental frequency; 
 a frequency-domain to time-domain transformer operable to transform said frequency components extracted by said bandwidth limiter to a time-domain signal; and 
 an amplitude corrector operable to multiply said time-domain signal by a reciprocal of said window function to generate said analytic signal, and 
 wherein said waveform data selector selects said signal part to partially overlap a previously selected signal part. 
 
   
   
     30. A measuring apparatus as claimed in  claim 27 , wherein said bandwidth limiter extracts a desired frequency band. 
   
   
     31. A measuring apparatus as claimed in  claim 23 , wherein said timing jitter estimator includes an waveform clipper operable to remove amplitude modulation components of said first and second signals and to supply said first and second signals without said amplitude modulation components to said analytic signal transformer. 
   
   
     32. A measuring apparatus as claimed in  claim 25 , wherein said timing jitter calculator further includes a low frequency component remover operable to remove low frequency components of said instantaneous phase noise and to supply said instantaneous phase noise without said low frequency components to said resampler. 
   
   
     33. A measuring apparatus for performing a measurement for an electronic circuit, comprising:
 an instantaneous phase noise calculator operable to calculate a first instantaneous phase noise of a first signal and a second instantaneous phase noise of a second signal, said first signal being supplied to said electronic circuit or generated by said electronic circuit, said second signal being generated by said electronic circuit; and 
 a jitter transfer function estimator operable to calculate a jitter transfer function between said first and second signals based on frequency components of said first and second instantaneous phase noises. 
 
   
   
     34. A measuring method for measuring jitter characteristics of an electronic circuit, comprising:
 calculating a first timing jitter sequence of a first signal and a second timing jitter sequence of a second signal, said first signal being supplied to said electronic circuit or generated by said electronic circuit, said second signal being generated by said electronic circuit; and 
 calculating a jitter transfer function between said first and second signals based on frequency components of said first and second timing sequences. 
 
   
   
     35. A measuring method as claimed in  claim 34 , further comprising calculating jitter related transmission penalty of said electronic circuit based on said jitter transfer function. 
   
   
     36. A measuring method as claimed in  claim 35 , wherein said calculation of jitter related transmission penalty includes calculation of a bit error rate of said electronic circuit based on said jitter transfer function. 
   
   
     37. A measuring method as claimed in  claim 35 , wherein said calculation of jitter related transmission penalty includes calculation of jitter tolerance of said electronic circuit based on said jitter transfer function. 
   
   
     38. A measuring method for performing a measurement for an electronic circuit, comprising:
 calculating a first instantaneous phase noise of a first signal and a second instantaneous phase noise of a second signal, said first signal being supplied to said electronic circuit or generated by said electronic circuit, said second signal being generated by said electronic circuit; and 
 calculating a jitter transfer function between said first and second signals based on frequency components of said first and second instantaneous phase noises. 
 
   
   
     39. A measuring apparatus as claimed in  claim 28 , wherein said bandwidth limiter extracts a desired frequency band. 
   
   
     40. A measuring apparatus as claimed in  claim 29 , wherein said bandwidth limiter extracts a desired frequency band.